Lubricating compositions



United States Patent LUBRICATING COMPOSITIONS GeorgeM.Calhoun,llerkeley,Calif.,toShell 0lICompany,aeorpontionofDehware No Drawing. Filed Dee-16, 1957, Ser. No. 702,749 9 Claims. (Cl. 252-34) This invention relates to lubricants, particularly those suitable for lubrication under severe operating conditions, such as under extreme pressure and at high temperatures.

It is well known that the high pressure occurring in certain types of gears and bearings may cause rupture of lubricant films with consequent damage to the machinery. It has been shown that various base lubricants can be improved in their protective properties for rubbing surfaces by the addition of certain substances, so-called extreme pressure agents, so that excessive wear, scufiing and seizure which normally follow a break in the lubricant film can be minimized.

The art discloses that one of the most efiective means of imparting extreme pressure properties to lubricants is by the incorporation of a minor amount of an oil-insoluble polycarboxylic acid, such as tartaric acid, citric acid and the like. In order to stably disperse or solubilize extreme pressure agents of this type in a lubricant such as mineral oil, various solubilizers have been proposed, such as non-ionic products e.g. polyalkylene oxides and derivatives thereof, partial esters of fatty acids and alkanepolyols and mixtures thereof. As a rule it has been observed that solubilizers either interfere with or reduce the extreme pressure activity of the oil-insoluble polycarboylic acids in oils. Other means of solubilizing oilinsoluble polycarboxylic acids in mineral oils is by esterification of these polycarboxylic acids with long-chain alphatic alcohols such as octadecanol or by forming polyvalent metal salts of these acids. However, modification of the polycarboxylic acids in this manner substantially destroys the extreme pressure activity of the polycarboxylic acids.

It has now been discovered that improved stable extreme pressure lubricants are provided by a suitable lubricating oil containing a small amount of a complex obtained by admixing at a temperature ranging from about room temperature to about 85 C., approximately equivalent amounts of (1) an oil-insoluble aliphatic polycarboxylic acid, preferably an oil-insoluble aliphatic dicarboxylic acid, (2) a marginally oil-soluble high molecular weight fatty acid, preferably a C,-,-C saturated or unsaturated aliphatic monocarboxylic acid, and (3) an oil-soluble long chain aliphatic amine, preferably an oil soluble highly branched-chain aliphatic amine.

The oil-insoluble aliphatic polycarboxylic acids include acids such as unsubstituted aliphatic dicarboxylic acids e.g. oxalic, malonic, succinic, glutaric, adipic, pimelic, sebacic, azelaic and suberic acids, and hydroxypolycarboxylic acids e.g. tartaric and citric acids and the like. These acids may contain short alkyl radicals of from 1 to 4 carbon atoms each and a total of no more than about six carbons in all such alkyl radicals, as, for instance, mono-, di-, and tri-, methylor ethylor monobutyl glutaric, adipic, pimelic or suberic acids. Specific acids of this class are 2-methylglutaric acid, 2-methyladipic acid, 2-methylpimelic acid, Z-methylsuberic acid, 3-methylglutaric acid, 3-methyladipic acid, 3-methylpimelic acid, 3- methylsuberic acid, 2,2-dimethy1glutaric acid, 2,2-dimethyladipic acid, 2,3-dimethylglutaric acid, 2,3-dimethyladipic acid, 3,3-dimetbyladipic acid, 2,4-dimethyladipic acid,

' 2,2,4-trimethyladipic acid, 2,3,4-trimethyladipic acid, 2,2,-

4-trimethylsuberic acid, 3-ethylglutaric acid, 2-methyl-3- ethyladipic acid, 2-methyl-4butylsuberic acid and mixtures thereof. The nonsubstituted dicarboxylic acids are preferred, including mixtures thereof.

The high molecular weight fatty acids useful for purposes of the invention are saturated and unsaturated C -C fatty acids, e.g. lauric, palmitic, myristic, stearic, oleic, linoleic, ricinoleic acids and the like.

The other component of the complex is an alpihatic amine which may be either a primary, secondary or tertiary, saturated or unsaturated, straight or branchedchain, aliphatic amine having at least 8 carbon atoms, preferably a saturated branched-chain aliphatic primary amine having from 12 to 24 carbon atoms. The saturated straight chain aliphatic tertiary amines having 12 to 24 carbon atoms are also especially useful although the primary branched-chain amines are preferred. Typical of the broad class of such aminesare monoamines such as octylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylarnine, octadecenylamine, octadccadienylamine, dioctylamine, didodecylamine, dioctadecylamine, dioctadecadienylamine, lauryl dimethylamine, octadecyldimethylamine and amines derived from fatty oils or fats such as cottonseed oil, soybean oil, cocoanut oil, I lard, tallow, and the like, such as soyamine, cocoamine,

tallowamine and mixtures thereof. Also useful are N- Table l Alkylamlne 5.1" Alkylamine "A1" Formula Principally Principally t-CnHuNHs t-Cil uN'H: t-CuHnNHs. t-CnHuNHs- Molecular Weight Principally Principally -227. Average Molecular Wei ht--- 315. Specific Gravity at 25 0.840. Refractive Index at 25 C"... 1.423 1.456. Boiling Point (or range) 53-90% at 223-240 540% at 265-308 C-. (760 mm.). C. (760 mm.)..

The tertiary alkyl primary amines, containing as the tertiary alkyl radical, the radical of polyisobutylene, polypropylene and mixtures thereof are particularly effective for the purpose of the present invention. They include l,l,3,3,5,5-hexamethylhexylamine (from triisobutylene), 1,1,3,3,5,5,7,7-octamethyloctylamine (from tetraisobutylene) and 1,1,3,3,5,5,7,7,9,9-decamethyldecylamine (from pentaisobutylene) are specific preferred amines, which are suitably used individually or as mixtures thereof. In addition to these tertiary alkyl primary amines, tertiaryalkylmethyl primary amines, such as 2,2,4,4-tetramethylpentylamine, 2,2,4,4,6,6-hexamethylheptylamine and the like are suitable. Other tertiaryalkyl primary amines which can be used include the C, and higher amines of this type mentioned in US. Patents 2,160,058, 2,606,923 and 2,611,782, such as tert-tridecylamine I 3 as well as isoheptyldiethylcarbinylamine, isooctylethylpropylcarbinylamine, and the like.

The complex is simple to prepare and involves admixing the three reactants (polycarboxylic acid, monocarboxylic acid and amine) in equivalent amounts at a temperature ranging from room temperature to about 85 C. in a non-polar medium such as a light hydrocarbon such as benzene or hydrocarbon oils. It is essential that no water or amides are formed during the formation of the complex. This is accomplished by controlling the temperature during the admixture of the above materials so that the temperature does not rise above 85 C. If during the admixing the temperature is allowed to increase above 85 C., say to 100 C. or higher, then a reaction product forms which has poor extreme pressure properties.

Examples of complexes useful as oil additives include equivalent weight mixtures of (l) adipic acid-lauric acid- A (2) adipic acid-lauric acid-lauryldimethylamine, (3) d-tartaric acid-lauric acid-A (4) sebacic acidlauric acid-A (5) oxalic acid-stearic acid-octadecylamine, (6) adipic acid-oleic acid-A (7) citric acidlaun'c acid-hexadecylamine, (8) azelaic acid-lauric acidoctadecylamine, (9) succinic acid-stearic acid-octadecyldimethylamine, (10) tartaric acid-oleic acid-1,1,3,3,5,5,- 7,7-octamethyloctylamine. Preferred complexes are: (A) 5% adipic acid-13.7% lauric acid-13.1% A (B) 5% adipic acid-13.7% lauric acid14.6% lauryldimethylamine, (C) 5% d-tartaric acid-13.25% lauric acid-12.75% A 3.3% 2-propanol, (D) 5% sebacic acid9.9% lauric acid9.5% A

In the above examples the materials were admixed at a temperature within the range of from room temperature to 85 C. until a homogeneous liquid formed.

The complex is useful in oils in amounts ranging from 0.1% to 15%, preferably from 1% to 10% by weight.

If desired, a small amount of from 0.1% to 5% of a clarifier e.g. an alkanol, can be added to lubricants of this invention. Such clarifiers include aliphatic alcohols having 2 to 18 carbon atoms per molecule, such as ethanol, propanol, hexanol or the so-called x0 alcohols derived from branched-chain olefins, such as polymers of lower alkenes of 3 to carbon atoms, and copolymers of mixtures of such alkenes, by catalyzed reaction with carbon monoxide and hydrogen in accordance with the conditions of the 0x0 process, as is well known in the art. The composition of a typical C -Oxo-alcohol mixture derived from a mixture of C olefins, produced by polymerization of a typical refinery cracked gas fraction of C -C hydrocarbons, is given in Table II.

Table 11 Alcohol Percent, wt.

3,5-dlmethyl hexanol 4,5-dimethyl hexanol 3,4dimethyl hexanol B-methyl heptanol If 3-methyl heptanol 5-ethy1 hexanol 5,5-dimethyl hexanol alpha-alkyl alkanols Others 111 hydrocarbon oils are petroleum motor oil (A) which is paralfinic in character and petroleum motor oil (B) which is naphthenic in character; they have the following properties:

Other suitable oils are represented by gas turbine lube oils having the following properties:

Grade 1010 1065 Flash, 000, 1" 300 465 Pour, F 10 0 Viscosity. SUS at 100 F 60. 4 53) Neutral Number 0.02 0.01 Ash None None With 5% of additives A (5% adipic acid-13.7% lauric acid--l3.1% A 13 (5% adipic acid13.7% lauric acid14.6% lauryldimethylamine), C (5% dtartaric acid-13.25% lauric acid-12.75% A 3.3% 2-propanol) or D (5% sebacic acid-9.9% lauric acid 9.5% A in 1010 mineral oil gave load values (lbs./ in.) in the spur gear machine of from 2200 to 2500, whereas neat 1010 mineral oil carried a load of 600 lbs./in. Mixtures of polycarboxylic acids such as adipic acid, sebacic acid or tartaric acid with amines such as A or lauryldimethylamine resulted in oil-insoluble products which when added to mineral oil could not be tested in the spur gear machine. Also a reaction product between an amine e.g. A and a fatty acid 'e.g. lauric acid when added to mineral oil resulted in a gel.

The complexes of this invention are useful also for providing superior load carrying properties in lubricating oils which contain minor amounts of other agents such as silicone anti-foaming agents, alkylphenol anti-oxidants, polyacrylate ester viscosity-index improvers, and the like.

I claim as my invention:

1. A lubricating composition comprising a major amount of lubricating oil and a minor amount sufficient to impart extreme pressure properties to the oil of an oilsoluble complex obtained by reacting at a temperature of from about room temperature to about C. and in equivalent amounts an oil-insoluble unsubstituted aliphatic dicarboxylic acid, said aliphatic portion of the molecule which separates the two acid groups having C carbon atoms, a marginally oil-soluble fatty acid having from 8 to 18 carbon atoms and an oil-soluble aliphatic amine having 8 to 24 carbon atoms.

2. A lubricating composition comprising a major amount of a mineral lubricating oil and a minor amount sufiicient to impart extreme pressure properties to the oil of an oil-soluble complex obtained by reacting at a temperature of from about room temperature to about 85 C. and in equivalent amounts an oil-insoluble unsubstituted aliphatic dicarboxylic acid, said aliphatic portion of the molecule which separates the two acid groups having C carbon atoms, an oil-soluble fatty acid having from 12 to 18 carbon atoms and an oil-soluble aliphatic amine having 8 to 24 carbon atoms.

3. A lubricating composition comprising a major amount of a mineral lubricating oil and a minor amount, suflicient to impart extreme pressure properties to the oil of an oil-soluble complex obtained by reacting at a temperature of from about room temperature to about 85 C. and in equivalent amounts an oil-insoluble unsubstituted aliphatic dicarboxylic acid, said aliphatic portion of the molecule which separates the two acid groups having C carbon atoms, an oil-soluble fatty acid having from 5 12 to 18 carbon atoms and an oil-soluble saturated straight-chain alkyl amine having 8-24 carbon atoms.

4. A lubricating composition comprising a major amount of a mineral lubricating oil and a minor amount, suficient to impart extreme pressure properties to the oil of an oil-soluble complex obtained by reacting at a temperature of from about room temperature to about 85 C. and in equivalent amounts an oil-insoluble unsubstituted aliphatic dicarboxylic acid, said aliphatic portion of the molecule which separates the two acid groups having C carbon atoms, an oil-soluble fatty acid having from 12 to 18 carbon atoms and an oil-soluble saturated branched-chain alkyl amine having 12-24 carbon atoms.

.5. A lubricating composition comprising a major amount of a mineral lubricating oil and a minor amount suflicient to impart extreme pressure properties to the oil of an oil-soluble complex obtained by reacting at a temperature of from about room temperature to about 85 C. and in equivalent amounts adipic acid, lauric acid and a saturated straight-chain primary aliphatic amine having 12-24 carbon atoms.

6. A lubricating composition comprising a major amount of a mineral lubricating oil and a minor amount auficient to impart extreme pressure properties to the oil of an oil-soluble complex obtained by reacting at a temperature of from about room temperature to about 85' C. and in equivalent amounts adipic acid, lauric acid and a saturated branched-chain primary aliphatic amine having 12-24 carbon atoms.

7. A lubricating composition comprising a major amount of a mineral lubricating oil and a minor amount suflicient to impart extreme pressure properties to the oil of an oil-soluble complex obtained by reacting at a temperature of from about. room temperature to about 85' C. and in equivalent amounts sebacic acid, lauric acid and a saturated branched-chain primary aliphatic amine having 12-24 carbon atoms.

8. A lubricating composition comprising a major amount of a mineral lubricating oil and a minor amount suflicient to impart extreme pressure properties to the oilof an oil-soluble complex obtained by reacting at a temperature of from about room temperature to about 85 C. and in equivalent amounts adipic acid, lauric acid and lauryldimethylamine.

9. A lubricating composition comprising a major amount of a mineral lubricating oil and a minor amount sufiicient to impart extreme pressure properties to the oil of an oil-soluble complex obtained by reacting at a temperature of from about room temperature to about 85 C. and in equivalent amounts adipic acid, lauric acid and a primary tertiary C -C alkyl amine.

References Cited in the file of this patent UNITED STATES PATENTS 2,490,744 Trigg et al. Dec. 6, 1949 2,594,286 Bryant et al. Apr. 29, 1952 2,758,086 Stuart et al. Aug. 7, 1956 2,788,326 Bondi et al. a Apr. 9, 1957 FOREIGN PATENTS 750,340 Great Britain June 13, 1956 OTHER REFERENCES I. and E. Chem.," vol. 42, No. 9, Sept. 1950, pages 1837-1841. 

1. A LUBRICATING COMPOSITION COMPRISING A MAJOR AMOUNT OF LUBRICATING OIL AND A MINOR AMOUNT SUFFICIENT TO IMPART EXTREME PRESSURE PROPERTIES TO THE OIL OF AN OILSOLUBLE COMPLEX OBTAINED BY REACTING AT A TEMPERATURE OF FROM ABOUT ROOM TEMPERATURE TO ABOUT 85*C. AND IN EQUIVALENT AMOUNTS AN OIL-INSOLUBLE UNSUBSTITUTED ALIPHATIC DICARBOXYLIC ACID, SAID ALIPHATIC PORTION OF THE MOLECULE WHICH SEPARATES THE TWO ACID GROUPS HAVING C4-8 CARBON ATOMS, A MARGINALLY OIL-SOLUBLE FATTY ACID HAVING FROM 8 TO 18 CARBON ATOMS AND AN OIL-SOLUBLE ALIPHATIC AMINE HAVING 8 TO 24 CARBON ATOMS. 